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<table width="100%" summary="page for summer and winter data"><tr><td>summer and winter data</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Air pollution data, separately for summer and winter months</h2>

<h3>Description</h3>

<p>Air pollution data from Leeds (U.K.) city centre, collected from 1994 to
1998. The <code>summer</code> data set corresponds to the months of April to July
inclusive. The <code>winter</code> data set corresponds to the months of November
to February inclusive. Some outliers have been removed, as discussed by
Heffernan and Tawn, 2004.
</p>


<h3>Format</h3>

<p>Data frames with 578 (summer) and 532 (winter) observations on the
following 5 variables.
</p>

<dl>
<dt>O3</dt><dd><p>Daily maximum ozone in
parts per billion.</p>
</dd>
<dt>NO2</dt><dd><p>Daily maximum NO2 in parts per
billion.</p>
</dd>
<dt>NO</dt><dd><p>Daily maximum NO in parts per billion.</p>
</dd>
<dt>SO2</dt><dd><p>Daily maximum SO2 in parts per billion.</p>
</dd>
<dt>PM10</dt><dd><p>Daily maximum PM10 in micrograms/metre^3</p>
</dd>
</dl>



<h3>Source</h3>

<p>Provided as online supplementary material to Heffernan and Tawn,
2004:
</p>
<p>http://www.blackwellpublishing.com/rss/Readmefiles/heffernan.htm
</p>


<h3>References</h3>

<p>J. E. Heffernan and J. A. Tawn, A conditional approach for
multivariate extreme values, Journal of the Royal Statistical society B, 66,
497 &ndash; 546, 2004
</p>


<h3>Examples</h3>

<pre>

data(summer)
data(winter)

</pre>


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